It is known, particularly in certain areas of acoustics and seismics, to interpret pressure and particle velocity measurements as representative of Green's functions or equivalent functions representing the influence that the medium supporting the wave propagation has on a traveling wave or wavefield. Examples of the methods applied in this field can be found for example in:    A. J. Berkhout, D. de Vries, and P. Vogel, 1993, Acoustic control by wave field synthesis: J. Acoust. Soc. Am. 93 (5), 2764-2778;    A. J. Berkhout, D. de Vries, and J. J. Sonke, 1997, Array technology for acoustic wave field analysis in enclosures: J. Acoust. Soc. Am. 102 (5), 2757-2770;    Cassereau, D., and M. Fink, 1993, Focusing with plane time-reversal mirrors: An efficient alternative to closed cavities: J. Acoust. Soc. Am., 94, 2373-2386;    Grote, M., and C. Kirsch, 2007, Nonreflecting Boundary Conditions for Time Dependent Multiple Scattering, J. Comp. Physics, 221, 41-62;    Grote, M., and I. Sim, 2011, Local Nonreflecting Boundary Conditions for Time Dependent Multiple Scattering, J. Comp. Phys. 230, 3135-3154;    Lim, H., S. V. Utyuzhnikov, Y. W. Lam, A. Turan, M. R. Avis, V. S. Ryanebkii, and T. S. Tsynkov, 2009, Experimental validation of the active noise control methodology based on difference potentials: AIAA Journal, 47, 874-884;    van Manen, D. J., Robertsson, J. O. A., and Curtis, A., 2007, Exact wave field simulation for finite-volume scattering problems: J. Acoust. Soc. Am., 122, EL115-EL121;    van Manen, Robertsson, Curtis, 2010, Method of evaluating the interaction between a wavefield and a solid body, U.S. Pat. No. 7,715,985B2;    Thomson, C. J., 2012, Research Note: Internal/external seismic source wavefield separation and cancellation: Geophysical Prospecting, DOI: 10.1111/j.1365-2478.2011.01043.x;    Utyuzhnikov, S. V., 2010, Non-stationary problem of active sound control in bounded domains: J. Comp. Appl. Math., 234, 1725-1731; and    Ffowcs Williams, J. E., 1984, Anti-sound: Proceeding of the Royal Society of London A, 395, 63-88.    van Manen et al. (2007, 2010) introduced so-called exact boundary conditions (EBC's). These allow for two wave propagation states in a numerical simulation to be coupled together. In particular van Manen et al. (2007) studied the problem of recomputing synthetic seismic data on a model after making local model alterations. EBC's enable to completely account for all long-range interactions while limiting the recomputation to a small model just around the region of change. van Manen et al. (2007) outlined the basic theory and demonstrated it on a ID example. Related concepts were recently proposed by Grote and Kirsch (2007), Grote and Sim (2011), Thomson (2012) and Utyuzhnikov (2010).
The concept of noise cancellation is widely known in the field of acoustic signal processing as described for example by Ffowcs Williams (1984) and Lim et al. (2009). In active noise cancellation a wave signal is recorded using an acoustic transducer (microphone), processed to generate a phase-inverted signal, and emitted by transducers (loudspeakers) to interfere destructively such that the listener no longer hears the original noise.
It is seen as an object of the invention to create a virtual sound environment for a listener such that the listener perceives to be located—at least acoustically—in an environment different from the actual one.